GPT on Question 21, Sep 17

In the 18th century, black powder was manufactured in specialized powder mills from three ingredients: saltpeter (potassium nitrate), charcoal, and sulfur. Production was dangerous and increasingly regulated, so governments often controlled mills or contracted with licensed manufacturers.

A typical historical process involved:

• 1.Purifying raw materials
• •Saltpeter, obtained from mineral deposits or nitrate-rich soils, was dissolved, filtered, and recrystallized.
• •Sulfur was refined to remove impurities.
• •Charcoal was made from selected woods in low-oxygen ovens; its quality strongly affected the powder.

• 2.Grinding the ingredients separately
  Each material was reduced to a fine, consistent powder. Separate grinding reduced—but did not eliminate—the risk of accidental ignition.

• 3.Incorporating them
  The ingredients were blended and worked together in an “incorporating mill,” often using heavy wooden or stone wheels driven by waterpower. The mixture was kept slightly damp to reduce dust and improve uniformity.

• 4.Pressing and “corning”
  The incorporated mass was compressed into dense cakes, then broken into grains. This corning process made the powder burn more predictably than the older practice of using it as loose “meal powder.”

• 5.Grading and finishing
  Sieves separated grains by size for different uses, such as muskets, cannon, blasting, or priming. Some powder was tumbled or “glazed” to smooth the grains, reduce dust, and improve resistance to moisture.

• 6.Drying and packing
  The grains were dried in carefully isolated buildings and packed in wooden barrels or other non-sparking containers.

Powder mills were deliberately divided into separate, lightly constructed buildings spaced apart, so an explosion in one stage would be less likely to destroy the entire works. Workers used non-sparking tools, avoided iron fittings where possible, and followed strict rules concerning fire, footwear, and clothing—although catastrophic accidents remained common.